This protocol is designed to evaluate the safety, tolerance and potential efficacy of at least three (and possibly four) dosages (1.0, 5.0 and 25.0 mg/kg plus possibly an intermediate dose between either 1.0 and 5.0 mg/kg or 5.0 and 25.0 mg/kg) of a human anticytomegalovirus monoclonal antibody, PDL MSL-109, in the treatment of neonates with congenital cytomegalovirus infection. Outpatient treatment will be provided at the GCRC for six weeks and then intermittently for five years. Laboratory work and physical assessment including brain stem evoked response, pure tone audiometry, tympanometry, phthalmology, Denver Developmental and Wechsler Intelligence assessments will be done a maximum of 5-8 times during treatment, allowing us to assess the potential benefits/risks of MSL-109 in congenital cytomegalovirus infection.